Add test to design warns signature in TDD mimicking raises signature

Author: Joan Massich

testing/test_recwarn.py

@@ -284,3 +284,25 @@ def test(run):
         ''')
         result = testdir.runpytest()
         result.stdout.fnmatch_lines(['*2 passed in*'])
+
+    def test_match_regex(self):
+        with pytest.warns(UserWarning, match=r'must be \d+$'):
+            warnings.warn("value must be 42", UserWarning)
+
+        with pytest.raises(AssertionError, match='pattern not found'):
+            with pytest.warns(UserWarning, match=r'must be \d+$'):
+                warnings.warn("this is not here", UserWarning)
+
+    def test_one_from_multiple_warns():
+        with warns(UserWarning, match=r'aaa'):
+            warnings.warn("cccccccccc", UserWarning)
+            warnings.warn("bbbbbbbbbb", UserWarning)
+            warnings.warn("aaaaaaaaaa", UserWarning)
+
+    def test_none_of_multiple_warns():
+        a, b, c = ('aaa', 'bbbbbbbbbb', 'cccccccccc')
+        expected_msg = "'{}' pattern not found in \['{}', '{}'\]".format(a, b, c)
+        with raises(AssertionError, match=expected_msg):
+            with warns(UserWarning, match=r'aaa'):
+                warnings.warn("bbbbbbbbbb", UserWarning)
+                warnings.warn("cccccccccc", UserWarning)